Method of and compositions for bleaching in acid solutions



United States Patent 2,993,745 METHOD OF AND COMPOSITIONS FOR BLEACHINGIN ACID SOLUTIONS Rowell R. Dorsett, Baltimore, Md., assiguor ofone-half 5 to Mangels, Herold Company, Inc., Baltimore, Md., acorporation No Drawing. Filed July 27, 1956, Ser. No. 600,400

7 Claims. (Cl. 8-108) This invention relates to the bleaching of nylon,cellulosicmaterials, regenerated cellulosic materials and fibers orfilaments of the polyesters while at the same time. inhibiting thedegradation of suchv materials by the active bleaching chlorine, and tobleaching compositions which are effective inacid solutions and containan inhibiting agent to prevent degradation of the materials mentionedwhile being bleached.

This application is a; continuation-in-part ofv my copending applicationSerial No. 517,069, :filed June 21, 1955, nowabandoned.

Materials such as nylon, cellulosic materials, regenerated cellulosicmaterials and fibers or filaments of-the polyesters are very sensitiveto bleaching agents and are degraded-bythem. Nylon ,par t-icularv isveryv diificult to bleach and -is degraded by alkaline bleachingcompounds There are compounds available which yield-activeorbleaching'chlorine in both alkaline and acid soluti9ns,- Butthe se compounds ifnot. usedin acid solution agents inhibiting degradation by the active orbleachingchlgrine, are very.'destructiveof the type ofmaterials 30 abgvemntioned.

I have found that trichlorocyanuric acid and dichlord cyanu ric acidwhenused in alkaline solutions will degrade jniaterials-such as;nylon,cellulosic materials, regenerated m thod of bleaszhinsu g c u o i' jt if i e l 'ated celiulesie materialrand fibers or'filaments' offthe.polyesters in an acidic ,solutioncontaining as the active bleach- "mg aent riclilbro cyanuric acid'ordichlorocyanuric acid, anil an inhibitingagent selected from theniolecularly deh fated phosphates of-the groupconsisting ofthe alkali 'diltal' phosphate-glasse's ih whichttheratio ofM 010 R 0 eam-0:51 lito abdut: 1.7:: 1, "where M'zis sodium,potasinsium; orizarnmoniu m andi-the c riystallineualkalimetalmoleeularly; dehydratedphosphates {such as the sodium; or potassium n sp ph es: ('jNasle m rK 3010) i 1 uit-reta ium: PY PJ QSPh a tiai a q.and Kin-201 a l?.iher mdilqsmi aid Pv e ,Pha i i-(Naeflz aQ'r ml; 2 2P2Q- I11 .p par' 'ng. il

"leaching solutiori stifii'cient oft-he bleachin agent, ther trich acidis added "of available ob to be etcii d'i b t a new 'complished; For"the ordinary domesti V bleaching the concentration of availableehionnemay be "or nausea-01d T 9 Patented July 2 5, 1961 ice of the order ofone percent. For heavy duty bleaching suchas encountered in commerciallaundries the amount of the bleaching agent added may be such as willprovide in the bleaching solution a concentration of from 500 p.p.m. to250,000 ppm. of available chlorine. The concentration may be made lowerthan that or higher depending upon the amount of the bleachingagenteither trichlorocyanuric acid or dichlorocyanuric acid, required.To protect the materials bleached from degradation by the active orbleaching chlorine, an inhibiting agent selected from the group of themolecularly dehydrated phosphates above mentioned, may be added inamount sufficient to prevent degradation; The amount of molecularlydehydrated phosphate added may vary from about. 1,000 ppm. toapproximately 400,000 ppm. In any case the molecularly dehydratedphosphate added could vary from twenty-five pounds to sixty or seventypounds per 100 pounds of water;

To the bleaching solution acidifying agents may be added in ordertoinsure that the pH thereof will be below 7, preferably in the rangefrom about 4.5 to 6.9.

Another object of the invention is to provide an eifectingbleachingcomposition in which the efiective or essential bleaching agentis selected from the class consisting of trichlorocyanuric acid anddichlorocyanuric acid and in which; the inhibiting agent is amolecularly dehydrated phosphate selected from the group consisting ofthe alkali metal phosphate glasses above mentioned and the alkaliditions of storage and transportation and which when dissolved in waterwill yield solutions suitable for bleaching, sterilizing anddisinfecting and particularly for the bleaching of materials such asnylon, cellulosic materials, regenerated cellulosic materials and fibersor filaments of the polyesters.

Other objects of the invention are to provide a composition as above setforth which is useful as a disinfecting detergent for laundry and otherpurposes, as a bleaching detergent composition for laundry and otherpurposes where protection against degradation of the bleached fabrics isessential. I

The above and other objects of the invention will be apparent to those'or ordinary skill in the art to which the invention pertains from thefollowing description.

A bleaching' composition embodying the invention may be preparedbymixing a compoundof the group consisting of tn'chlorocyanuric acid anddichlorocyanuric acid and an agent that is effective to inhibitdegradation of the materials suchas nylon, cellulosic materials,regenerated cellulosic materials and fibers or filaments of thepolyesters. The trichlorocyanuric acid and the dichlorocyanuric acid areavailable having a high available active chlorine content. If thesematerials have percent available chlorine, approximately 1.12 poundsthereof in pounds of water will yield about 1 percent availablechlorine. 'For the ordinary composition that would be used in thehousehold, itwould' contain sufiicient of the active acidic;bleachingagent to provide about 1 percent available=ehlorine,-. and. sufiicientinhibitinguagent to 'in the presence of the active bleaching agent.

22.5 parts by weight trichlorocyanuricacid 85 :.30 parts by weightsodium tripolyphosphate 3:0 parts by weight rnonosodium dihydrogenphosphate 17.5parts' by weight sodium phosphate glass I preventdegradation of the fabrics bleached in the solution. For the ordinarydomestic or household use the of available or active chlorine, theamount of agent. in

the composition which prevents degradation of the above mentionedmaterials will be such as to effectively achieve that result, namely theprevention of degradation.

The compositions in general may consist of the active bleachingagent-either the trichlorocyanuric acid or I the dichlorocyanuric acid,a molecularly dehydrated phosphate, an acidifying agent and a filler orneurtal material to give it bulk so that the composition may be usedwith economy and in the concentrations desired without accuratemeasurement.

The acidifying agents may be selected from among the compounds such assodium bisulphate, acetic acid, diacetic acid, sodium diacetate, citricacid, sulfamic acid and oxalic acid. The acidifying agents may alsoinclude monoalkali metal dihydrogen phosphate such as the sodium andpotassium dihydrogen phosphate.

The composition as above stated will contain a molecularly dehydratedphosphate selected from the group of phosphates above described. Forstorage purposes, that is stability in storage, the crystalline alkalimetal molecularly dehydrated phosphates are preferred to the molecularlydehydrated glassy phosphates;

The active bleaching agent i.e. either trichlorocyanuric acid ordichlorocyanuric acid, maybe'used to form'a bleaching detergentcomposition also. In such a composition, the detergent shall be'one thatis operative in acid solution, and which does not when in thecomposition, deteriorate in storage, cause the acidic bleaching agent tobreak down or which will not itself decompose I have found that Petro AAwhich is an alkyl naphthalene sulfonate, in powder form 98 percentactive, to be well suited for the formulation of the bleachingdeterg'entcomposition as it provides a product that is stable in storage, has along shelf life, remains free-flowing and does not deleteriously affectthe active bleaching agent.

The following are examples of the bleaching'composition:

Example 1 22.5 parts by weight of trichlorocyanuric acid 85 percentactive p 50 parts by weight sodium tripolyphosphate (Na P O 27.5 partsby weight sodium sulfate 4 Y A one percent solution of the compositionof Example II in tap water will have a pH of about 5.8 and will providean available chlorine content in a bleaching solution of about percent.This composition is useful in industrial sanitizing applications and forheavy duty bleaching.

Example III 11 parts by weight trichlorocyanuric acid 85 percentavailable chlorine 20 parts by weight sodium tripolyphosphate 15 partsby weight monosodium dihydrogen phosphate 54 parts by weight sodiumsulfate The pH of a one percent solution in tap water of the aboveExample III is about 6.1, the tap water having a pH of about 8.2. Thecomposition will provide an available chlorine content in the bleachingsolution of about 10 percent. In computing the available chlorinecontent in the solution it is to be remembered that 1 pound of The pH ofa one percent tap water solution of the above composition (Example I) is6.5 where the tap water itself had a pH ofv about 8.2. The compositionof Example I will provide an available chlorine content in a bleachingsolution of 19.125 or approximately 20 percent where 100 parts by weightof the composition is used in 100 partsby weight of water.

Thecomposition of Example I is' suitable for commercial bleachingapplications such as'are encountered in commercial laundries.

Example 11 7 percent 1 active chlorine the trichlorocyanuric acidpercent available active bleaching chlorine will provide .85 percent ofavailable chlorine in the solution.

The above composition is useful in heavy duty bleach ing and inindustrial sanitizing applications.

Example IV As stated supra Petro AA is an alkyl naphthalene sulfonate 98percent active and is a powder.- I

The pH of a 1 percent solution in tap water of Example IV is about 6.2and it will provide an available chlorine content in aqueous solution ofabout 7 percent when suflicient of the composition is added to thesolution to provide approximately 8 parts by weight of thetrichlorocyanuric acid for each 100 parts by w'eightof water.

In the foregoing examples dichloro-cyanuric acid may besubstituted forthe'trichlorocyanuric acid in substantially the same proportions byweight. The dichlorocyanu'ricacid has about 65% to" 70% availablechlorine according to the technical literature of manufacturers of thatproduct. 1

Furthermore, in the foregoing examples an acidifying agent selected fromthe group consisting of sodium bisulfate, acetic acid, diacetic acid,sodium diacetate, citric acid, sulfamic acid and oxalic acid may beadded to the compositions to insure that the solutions of the,compositions will be acidic in use and provide a pH in'the bleachingsolutions ranging from pH about 4.5 to about 6.9. ,It is preferred thatthe pH range be maintained between 5.5 and 6.1. I

Sodium bicarbonate may be effectively used with the acidifying agent. ii

From the foregoing examples it will be apparent that the proportions ofthe trichlorocyanuric acid and the dichloro-oyanuric acid used in thecompositions mayyary from about 8 parts by weight to about,22.5 partslbyweight. The upper concentration in parts by weight of thetrichlorocyanuric acid or the dichloro-cyanuric acid duty .a bleachingcomposition.

Unbleached Warp Filling Strength in pounds on Scott Tester 80 Solutioncontaining 500 parts per million oi trichlorocyenuric acidsolutionadjusted topH of about 5.5-goods bleached 30 minutes at 160 F-Solution containing 500 parts per million of trichlorocyenuric acid anda 20% solution of monosodium dihydrogen phosphate the solution ,ad ustedto pH of, about .5.6.goods bleached. 30 minutes at 160 F Bleachingsolution of calcium oxichloritc (0210 C1) 500 parts per million insolution pH 9.6-goods bleached 30 minutes at 160 F The tests of theabove tests show the initial strength of the unbleached goods, the lossin strength of the warp and the filling where the trichlorocyanunic aciddid not contain a phosphate, the strength after bleaching with phosphatein solution, the value showing only an insignificant loss in strength onthe warp and the filling.

The loss in strength resulting from the use of calcium oxychloride wasvery significant and substantial.

The following shows the results of bleaching useyellowed nylon garmentsin solution containing the trichlorocyanuric acid and sodium Lorolsulfate. The bleach bath contained 0.1% sodium Lorol sulfate and 1.13%trichlorocyanuric acid. The bleach bath was at a temperature of 70 C.,and the bleach cycle was two hours.

A set of seven (7) use-discolored fabrics having an average yellownessof 7.1 +b units as measured on a differential colorimeter had an averageyellowness of 3.1 +b units after bleaching in the above solution. Thisis an acceptable shade of whiteness.

In another test the following use-yellowed nylon garments having the +bvalue of whiteness indicated were bleached in a solution containingabout 1.13% by weight of the tn'chlorocyamiric acid.

Garment +b Value After bleaching +b Value After bleaching, the blousehaving the +b value of 2.5 had a reflectance b value of 2.5. The average+b values for the other garments was approximately 3.06.

, 6 acid was present in each oi? the following in amount suflicient to.yield about 1% available chlorine.

NB-rSO4, NanHzPror Na dlacetate NarS04, Oalgon, benzoic acid NazHzPro'l,synthetic detergent Acetic acid 7 N a Lcrol" sulfate (0.2%), Aceticacid.

Similar tests have indicated that similar results are obtainable by theemployment of dichlorocyanuric acid m lieu of trichlorocyanuric acid..Froni the vforegping it is apparent that a process has been providedwhereby material such as nylon, cellulosic materials, regeneratedcellulosic materials and fibers or filaments of the polyesters may bebleached or washed and bleached eifectively and safely in acidicsolutions containing trichlorocyanuric acid or dichlorocyanuric acidwithout suffering any substantial loss of strength through degradation.

It is also apparent that elfective bleaching compositions which areinhibited against the degradation of the above mentioned materials,including bleaching and detengent compositions having the sameproperties has been provided.

Having thus described the invention it will be apparent to those ofordinary in the art to which the invention pertains that variousmodifications and changes may be made in the described method and theexamples of the compositions without departing from either the spirit orthe scope of the invention.

Therefore, what is claimed as new and desired to be secured by LettersPatent is:

l. The method of bleaching fibers and filaments of nylon, cellulose,regenerated cellulose, and polyesters which consists of preparing anaqueous solution of an active bleaching agent of the group consisting oftrichlorocyanmic acid and dichlorocyanuric acid in amount suflicient toprovide about 1% to about 25% of available chlorine, and a degradationinhibiting agent selected from the class of phosphate consisting ofalkali metal molecularly dehydrated phosphate glass, alkali metaltripolyphosphate and alkali metal pyrophosphate, including alkali metalacid pyrophosphate, adjusting the pH of the solution to a value fromabout pH 4 to 6.9, soaking the materials to be bleached in the solution,rinsing, and removing the materials from the bleach and drying the same.

2. The method of claim 1 in which the pH of the solution is maintainedbetween pH 5 and pH 6.2 by monoalkali metal dihydrogen phosphate.

3. A bleaching composition for bleaching in acid solution fibers andfilaments of nylon, cellulose, regenerated cellulose and polyesterswhich comprises:

(a) An -8 to 25 by weight acid bleaching compound of the classconsisting of tn'chlorocyanuric acid and dichlorocyanuric acid computedon an available chlorine basis,

(b) Alkali metal molecularly dehydrated phosphate 25 to 50 percent byweight, and

(c) The balance consisting of a compound selected from the groupconsisting of sodium sulfate, and monoallcali metal dihydrogenphosphate.

4. A bleaching composition comprising:

(a) Trichlorocyanuric acid (85% available chlorine) 8 to 22.5 percent byweight,

(b) Alkali metal molecularly dehydrated phosphate 25 to 50 percent byweight, and

(c) Ari acidifying agent in amount suflicient to maintain a 1% solutionof the composition at a pH value from 4.5 to about 6.5.

5. A bleaching and detergent composition comprising v A composition asinc1ai1 n 6 containing an acidify- 8' 6 25% byjwei' ht at; bleaching aent} of the roup i i age t in amend; sum cieii to maint in the pHQof aconsistingoftriclilorocyaiinric acid 'dichldfocya'niific 1%"soh'l'tioii' of the compbsitldfi between 4.5 and 6.5. acid computed onan 85% available @5555 Ha sis ,'a'fid v i; I w: mole'cillal'lydehydrated phosphate 25 to 50 percent by 5 Reflences Cited in the tileof th is patent weight and a detergent consisting about 15% by weight 7N Efi" ST PATEN i 98% active the balance 1-,s912,s4s Feibelnta'nn Dec.27, 1932: conslstlng of actdrfmngagents. a o 2075 9113. San h v v I V 611937 -6. A bleaching'composition' for nylon; cellulosic and" 2121501 Hg: 1938: sirnilar materials; having as its active bleaching agenta: 102166362 53 compound of the class consisting of trichlorocyanuric 1 1 iand dichlorocyanuric acids and a degradation inhibiting et """"f'"f"J ep1947 agent selected from the" class of alkali metal molecu 25781270 3 69 1951 1am dehydrated phos'in'hatefglasses', the crystallinetrh2,607,738 1 p'olypliosphates and the crystallinepyrophosphatesy the 156111700 1 z 17932 ratio of the bleaching agent computed on an"85%"a\lai1 runner et able chlorine basis to inhibiting agent" percent ,by 'b EE S Weight being in the crange'of 8z2ifl to 25:50; and having 1 I s- H apHin 10% solution'between s and 6: 406,431 Italy 23, 19

1. THE METHOD OF BLEACHING FIBERS AND FILAMENTS OF NYLON, CELLULOSE,REGENERATED CELLULOSE, AND POLYESTERS WHICH CONSISTS OF PREPARING ANAQUEOUS SOLUTION OF AN ACTIVE BLEACHING AGENT OF THE GROUP CONSISTING OFTRICHLOROCYANURIC ACID AND DICHLOROCYANURIC ACID IN AMOUNT SUFFICIENT TOPROVIDE ABOUT 1% TO ABOUT 25% OF AVAILABLE CHLORINE, AND A DEGRADATIONINHIBITING AGENT SELECTED FROM THE CLASS OF PHOSPHATE CONSISTING OFALKALI METAL MOLECULARLY DEHYDRATED PHOSPHATE GLASS, ALKALI METALTRIPOLYPHOSPHATE AND ALKALI METAL PYROPHOSPHATE, INCLUDING ALKALI METALACID PYROPHOSPHATE, ADJUSTING THE PH OF THE SOLUTION TO A VALUE FROMABOUT PH 4 TO 6.9, SOAKING THE MATERIALS TO BE BLEACHED IN THE SOLUTION,RINSING, AND REMOVING THE MATERIALS FROM THE BLEACH AND DRYING THE SAME.